Open AccessPalmitate decreases proton pumping of liver‐type cytochrome c oxidase
Author(s) -
Lee Icksoo,
Kadenbach Bernhard
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.0014-2956.2001.02602.x
Subject(s) - cytochrome c oxidase , cardiolipin , chemistry , oxidase test , biochemistry , cytochrome , cytochrome c , inner mitochondrial membrane , stoichiometry , phospholipid , enzyme , mitochondrion , membrane , organic chemistry
The H + /e – stoichiometry of reconstituted cytochrome c oxidase from bovine kidney, containing subunit VIaL (liver type), is 0.5 under standard conditions but 1.0 on addition of 1% cardiolipin to the lipid mixture (asolectin). Low concentrations of palmitate (half‐maximal effect at 0.5 µ m ), but not laurate, myristate, stearate, oleate, 1‐hexadecanol, palmitoyl glycerol and palmitoyl CoA, decreased the H + /e – ratio in the presence of cardiolipin from 1.0 to 0.5, accompanied by an increase of coupled, but not of uncoupled respiration of proteoliposomes. Cardiolipin and palmitate did not influence the H + /e – stoichiometry and respiration of reconstituted cytochrome c oxidase from bovine heart, containing subunit VIaH (heart‐type). The H + /e – stoichiometry of the heart enzyme, however, is decreased from 1.0 to 0.5 by 5 m m intraliposomal ATP (instead of 5 m m ADP). It is assumed that palmitate binds to subunit VIaL. The partial uncoupling of proton pumping in cytochrome c oxidase is suggested to participate in mammalian thermogenesis.